The present invention relates generally to system arrangements for an electronic private automatic branch exchange and more particularly to a tie trunk control arrangement for an electronic private automatic branch exchange which is built around a space divided solid state matrix.
Tie trunks are generally known in the art to connect one private automatic branch exchange to another private automatic branch exchange while a central office (CO) trunk is used for the connection of a private automatic branch exchange to a central office. It is often necessary to provide additional circuitry in a private automatic branch exchange for differentiating the control functions of the system between central office (CO) trunks and tie trunks because of their diverse purposes. Advantageously, the additional circuitry and any operational differences between tie trunks and CO trunks of a system should be minimized. Tandem operation of a tie trunk and a CO trunk or two tie trunks through a tying PABX should be provided in such a system to allow a local station of a tied PABX to access a connected central office or another tied PABX. Also, it would be useful to provide attendant control of a tandem operation to obviate toll restriction requirements.
Recently, an electronic private automatic branch exchange which is build around a space divided rectangular solid state switching matrix was developed to provide an exchange which is more dependable in operation and less subject to misoperation due to interference, cross-talk and other problems.
In this exchange one side of the solid state matrix provides line appearances which are connected to line circuits, tone receivers, sender and operator loops. The other coordinate side of the matrix provides junctor appearances for connections to an attendant junctor, local junctor, tie trunk junctors, and trunk junctors. The solid state switching matrix is a single stage matrix providing direct connection between line appearances and junctor appearances by closing of a single crosspoint. The connection between lines within the system is effected simply by the interconnection of a pair of crosspoints associated with the respective lines in a selected junctor, thereby providing a greatly decreased amount of switching for establishing a connection through the matrix.
The electronic private automatic branch exchange providing the above features is more fully described in co-pending application, entitled, "Electronic Private Automatic Branch Exchange," Ser. No. 431,928, filed on Jan. 9, 1974, in the names of Uwe A. Pommerening and Glenn L. Richards, and assigned to the same assignee as the present application and the disclosure which is incorporated herein by reference.
A novel and advantageous trunk transfer circuit for the above electronic private automatic branch exchange is more fully described in a co-pending application, entitled, "Trunk Transfer Circuit," Ser. No. 561,744, filed on Mar. 25, 1975, in the name of Uwe A. Pommerening, assigned to the same assignee as the present application, the disclosure of which is herein incorporated by reference.
Further, a novel and useful trunk consultation arrangement incorporating the trunk transfer circuit is more fully described in a co-pending application, entitled, "Trunk Consultation Arrangement," Ser. No. 561,825, filed on Mar. 25, 1975, in the name of Uwe A. Pommerening, assigned to the same assignee as the present application, the disclosure which is herein incorporated by reference.